How to manage LVM volumes on CentOS / RHEL 7 with System Storage Manager

Logical Volume Manager (LVM) is an extremely flexible disk management scheme, allowing you to create and resize logical disk volumes off of multiple physical hard drives with no downtime. However, its powerful features come with the price of a somewhat steep learning curves, with more involved steps to set up LVM using multiple command line […]
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How to secure a LAMP server on CentOS or RHEL

LAMP is a software stack composed of Linux (an operating system as a base layer), Apache (a web server that “sits on top” of the OS), MySQL (or MariaDB, as a relational database management system), and finally PHP (a server-side scripting language that is used to process and display information stored in the database). In […]
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How to install Puppet server and client on CentOS and RHEL

As a system administrator acquires more and more systems to manage, automation of mundane tasks gets quite important. Many administrators adopted the way of writing custom scripts, that are simulating complex orchestration software. Unfortunately, scripts get obsolete, people who developed them leave, and without an enormous level of maintenance, after some time these scripts will […]
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How to check RPM package dependencies on Fedora, CentOS or RHEL

A typical RPM package on Red Hat-based systems requires all its dependent packages be installed to function properly. For end users, the complexity of such RPM dependency is hidden by package managers (e.g., yum or DNF) during package install/upgrade/removal process. However, if you are a sysadmin or a RPM maintainer, you need to be well-versed […]
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How to analyze Squid logs with SARG log analyzer on CentOS

In a previous tutorial, we show how to configure a transparent proxy with Squid on CentOS. Squid provides many useful features, but analyzing a raw Squid log file is not straightfoward. For example, how could you analyze the time stamps and the number of hits in the following Squid log? 1404788984.429 1162 172.17.1.23 TCP_MISS/302 436 […]
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How to set up Squid as a transparent web proxy on CentOS or RHEL

In a previous tutorial, we have seen the method of creating a gateway using iptables. This tutorial will focus on turning the gateway into a transparent proxy server. A proxy is called “transparent” when clients are not aware that their requests are processed through the proxy. There are several benefits of using a transparent proxy. […]
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How to run Docker containers on CentOS or Fedora

Lately Docker has emerged as a key technology for deploying applications in the cloud environment. Compared to traditional hardware virtualization, Docker-based container sandbox provides a number of advantages for application deployment environment, such as lightweight isolation, deployment portability, ease of maintenance, etc. Now Red Hat is steering community efforts in streamlining the management and deployment […]
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How to set up a secondary DNS server in CentOS

In the previous tutorial, we created a primary DNS server (ns1) for a test domain example.tst. In this tutorial, we will create a secondary DNS server (ns2) for the same domain by using bind package on CentOS. When it comes to setting up a secondary DNS server, the following factors should be kept in mind. […]
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How to set up a primary DNS server using CentOS

Any operational domain has at least two DNS servers, one being called a primary name server (ns1), and the other a secondary name server (ns2). These servers are typically operated for DNS failover: If one server goes down, the other server becomes an active DNS server. More sophisticated failover mechanisms involving load balancers, firewalls and […]
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